MicrobiologicalEvaluation of HouseholdDrinkingWaterTreatment in RuralChina Shows Benefits of ElectricKettles: A Cross-SectionalStudy.

Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America; School of Public Health, University of California, Berkeley, California, United States of America.

2

National Center for RuralWater Supply Technical Guidance, Chinese Center for Disease Control and Prevention, Beijing, China.

Department of Environmental Science, Policy and Management, University of California, Berkeley, California, United States of America.

5

School of Public Health, University of California, Berkeley, California, United States of America.

6

Energy and Resources Group, University of California, Berkeley, California, United States of America.

Abstract

BACKGROUND:

In ruralChina ~607 million people drink boiled water, yet little is known about prevailing householdwatertreatment (HWT) methods or their effectiveness. Boiling, the most common HWT method globally, is microbiologically effective, but household air pollution (HAP) from burning solid fuels causes cardiovascular and respiratory disease, and black carbon emissions exacerbate climate change. Boiled water is also easily re-contaminated. Our study was designed to identify the HWT methods used in ruralChina and to evaluate their effectiveness.

METHODS:

We used a geographically stratified cross-sectional design in rural Guangxi Province to collect survey data from 450 households in the summer of 2013. Householddrinkingwater samples were collected and assayed for Thermotolerant Coliforms (TTC), and physicochemical analyses were conducted for village drinkingwater sources. In the winter of 2013-2104, we surveyed 120 additional households and used remote sensors to corroborate self-reported boiling data.

CONCLUSION:

As far as we are aware, this is the first HWT-focused study in China, and the first to quantify the comparative advantage of boiling with electrickettles over pots. Our results suggest that electrickettles could be used to rapidly expand safe drinkingwater access and reduce HAP exposure in ruralChina.

A jitter of five was used to better display observation frequencies. Data exclude 38 TTC outlier cases. Drinkingwater samples from households using electrickettles were associated with the lowest mean Log10TTC concentrations. Scheffe’s multiple-comparison test showed mean Log10TTC for kettles and bottled water were both statistically significantly different than untreated (p<0.001 and p<0.01, respectively); Bonferroni test showed kettles, pots, and bottled water were significantly different than untreated (p<0.001, p<0.05, and p<0.01, respectively).

Each stacked bar displays TTC concentrations divided into categories based on likely health risk, and the percentage of households in each risk category by HWT method. The WHO’s standard for the microbiological safety of water using TTC as an indicator of fecal contamination is no detectable TTC/100mL []. The CCDC’s risk classification also considers TTC samples that are below the detection limit as microbiologically safe []. At counts of 1–9 MPN/100mL, if sanitary conditions are decent, drinkingwater is usually low risk for most people, except young children, the elderly, and the immunocompromised. Data exclude 38 TTC outlier cases (outlier inclusion yielded slightly larger proportions of households in the high risk category).